Process for coking pumpable animal and dairy wastes

ABSTRACT

Animal and dairy wastes are converted to deodorized coke suitable for use as fertilizer or soil conditioner, an aqueous odor-free effluent having low chemical oxygen demand and reduced phosphorus content and an odorless gas suitable for discharge to the atmosphere. The wastes are coked in the liquid phase under pressure to produce wet coke and a malodorous, gas-containing effluent high in chemical oxygen demand. The wet coke is treated with pressurized hot air to remove liquids therefrom and the air stream is mixed with the effluent and the mixture is oxidized, brought into heat exchange relationship with incoming wastes and then discharged.

United States Patent Hess et al.

[4 1 June 20, 1972 [54] PROCESS FOR COKING PUMPABLE ANIMAL AND DAIRY WASTES [72] Inventors: Howard V. Hess, Glenham; Edward L.

Cole, Fishkill, both of N.Y.

[73] Assignee: Texaco Inc., New York, N.Y.

[22] Filed: Sept. 9, 1970 [21] Appl. No.: 70,775

3,272,740 9/ 1966 Gitchel et al ..1 10/8 X 3,275,547 9/1966 Bucksteeg et al ..201/25 X Primary Examiner-Norman Yudkofi Assistant Examiner-D. Edwards Att0rneyThomas H. Whaley and Carl G. Reis ABSTRACT Animal and dairy wastes are converted to deodorized coke suitable for use as fertilizer or soil conditioner, an aqueous odor-free effluent having low chemical oxygen demand and reduced phosphorus content and an odorless gas suitable for discharge to the atmosphere. The wastes are coked in the liquid phase under pressure to produce wet coke and a malodorous, gas-containing effluent high in chemical oxygen demand. The wet coke is treated with pressurized hot air to remove liquids therefrom and the air stream is mixed with the effluent and the mixture is oxidized, brought into heat exchange relationship with incoming wastes and then discharged.

5 Claims, 1 Drawing figure DRY, DEODORIZED COKE PATENTEUmzo m2 960 SNEQQSQ EQ 1 2 PROCESS FOR COKING PUMPABLE ANIMAL AND coke which is recovered is relatively high in phosphorus con- DAIRY WASTES tent which enhances its value as a soil conditioner and fertilizer. BACKGROUND OF THE INVENTION 5 The process of the invention will be better understood by 1-l :1eld0ftheIm/ent1n reference to the accompanying FIGURE showing diagram- Th Invention relates to a new and p Process for matically apreferred embodiment of the present invention.

r lng 1111 1 n dalry Wastes, more partlcularly, t 3 To provide a basis for showing the advantages of the present more efficient and economical means of treating liquid animal process over h ki process ab -outlined, a sample of wastes than the bacterial decomposition or other presently 10 cattle waste b i d f a r ial dair and having a utlllzed P C chemical oxygen demand of 110,884 mg/O,/liter and an or- Th Scope of the Problem Of animal and dairy Waste (1181905111 ganic carbon content of 8.5 percent was coked in a coke drum has broadened in recent years because water pollution abateat 50 F. d 1,000 i Treatment f hi m waste ment regulations now demand more efiective control of waste ordin to the above ro e produced the following results discharge to streams and also because animal production in- (except for the oxidation step):

TABLE I Yield, weight Gross hcat Coke percent COD, Percent of comsurface Weight, basis mg. /Oi hustion, area, grams charge liter 0 S N P K II plI B.t.u./l b. M2/g Liquid phase coking of cow manure:

Charge-cow manure 710 Products from treating at 550 F., 1,150

p.s.i.g., 2 hours:

Aqueous efliueut. 530 'et coke 140 Gas (95% CO2) 28.4

Material balance 698. 4

Dry coke 56 Products from treating at 600 F., 1,875

p.s.i.g., 2 hours:

Aqueous eflluent 531 Wet coke 150 Gas (95% CO2) 33 Material balance 714 6 Dry coke 64 9.0 55.2 0.23 3.4 1.25 0.54 5.0 11,812 4 dustn'es are continuously being expanded to provide food for t In looking at the results shown in the table itbecomes apan ever-increasing world population. parent that the bulk of the phosphorus is rejected in the coke Description of the Prior Art product. In the run at 550 F., 95 percent of the phosphorus In eafhef times, and 110W around Small dairies and the like, and 60 percent of the nitrogen is removed from the system in the waste was collected and spread on the soil for fertilizer. 40 th k r d t, At 600 F., 98 percent of the phosphorus However, the concentration of waste from feed lot operations d 66 percent f h nitrogen i removed i h k 53 in lving p to 10,000 animals each n g does not allow cent of the sulfur is removed with the coke at 550 F. and 66 this method of disposal; for example, an average sample of r en at 600 F.

cattle waste contains about 90 percent water so that transpor- Th potassium content f h waste stream as i h b tatio" charges for hauling the waste y distance for fertilizer pected from the solubility of potassium salts in water, is largely Value would become pmhibitiveretained in the aqueous effluent from the coking operation. At

In a recently developed Process Organic wastes as 550 F. coking temperature 89 percent of the potassium Potato Peelings, Orange P y quid, newsprint remains in the aqueous effluent, at 600 F. coking temperature dust, etc. in water slurries have been coked under pressure to 86 percent produce an odorless coke, a gas which is suitable for venting It will be noted f Table I that the carbon distfibufion to the atmosphere, and a liquid eflluent which is not f am" at 550 malodorous and which is considerably reduced in COD Grams (Chemical Oxygen Demand). Attempts to apply this process Aqueous Emuem 214 264 to the purification of animal wastes, however, have not been Dry C ke 4.74 56.0 successful since the resulting effluent gases and coke are very Gas Tom 8 malodorous. The liquid efiluent, while being somewhat From the run at 600 reduced in COD by coking, still contains dissolved organic compounds which contribute to COD and make it undesirable Grim! for discharge into receiving lakes or streams. In addition the gg zf liquid efiluent has a bad odor due to these dissolved organic Gas L compounds. total: 8.48 100.0

SUMMARY OF THE INVENTION In accordance with the invention a pumpable animal or dairy waste stream is preheated, coked to form a gas phase, a

liquid phase (or aqueous coker effluent) and a wet coke phase; the wet coke phase is withdrawn intermittently, maineffluentr cat'bon'contammg water soluble compounds tained at a slightly superatmospheric pressure and deodorized are low molecular Y subject to coking with pressurized hot air, thereby simultaneously drying the under the rather mild coking condmons p y These It can be seen from the above (the carbon material balance from feed to products is 99.7 percent) that between 21.4 and 26.4 percent of the carbon remains dissolved in the aqueous coke. The new moist hot air is compressed and mixed with the materials of to the l chemical oxygen aqueous coker effluent and the product gases with the result- "land of the aqueous emllent Coming m h coking Operaing mixture being oxidized to destroy d f i tion. At 550 F. the aqueous efiluent from the coker still constituents therefrom. This oxidized stream is then heat tains 56 Percent of the COD Ofthe charge and at h exchanged with the incoming feed stream and the thus cooled q s effluent m h coker Con ains 50.5 percent of the effluent composed of gases and liquids can be finally disposed COD of the charge. This high COD of the aqueous eflluent of. The effluent is low in phosphorus and accordingly does not from the coking operation also results in the effluent having a contribute to algae growth in the receiving body of water. The very bad odor. This odor as well as the high COD makes it mandatory that additional treating be carried out before the effluent could be dumped into waterways. The wet coke produced in the operation, because it is wet with the aqueous coker efiluent, also has a foul odor and thus should also be treated before use as fertilizer or soil conditioner. Gases produced in the coking operation, even though they are roughly 95 percent CO also possess a foul odor and thus would require treatment before venting to the atmosphere.

In the embodiment of invention as shown in the figure, the waste stream is pumped up to system pressure in pump 1 through the heat exchanger 2 where it is in heat exchange with the oxidized effluent and through the heater 3 where the cokable materials are coked and from there to a decanter (held at system pressure) 4 where the system separates into a gas phase, a liquid phase (called aqueous coker effluent) and a wet coke phase. The wet coke phase is drawn down intermittently into vessel 5 which is maintained slightly above atmospheric pressure. Coke is now in the vessel 5 and to dry it and remove malodorous constituents, air is brought in at slightly above atmospheric pressure, preferably 30 to 60 psig, through the top part of heater 3 where it is heated to 250-350 F. (a temperature sufficient to dry and deodorize the wet coke) and passes through the sparger 12 shown at the bottom of vessel 5. The temperature range indicated suffices to dry and to deodorize the wet coke but is not sufficiently hot to burn the coke. The flow rate of hot air through the coke is sufficient to expand the coke bed and maintain it in an expanded condition above the sparger. In any case, sufficient air is used so that there will be an excess of oxygen available for burning the COD from the aqueous effluent and gases. Next, dry, deodorized coke is removed intermittently from the bottom of vessel 5 for use as fertilizer or soil conditioner. The warm, moist and now, smelly, air from vessel 5 is compressed in compressor 7 to system pressure and mixed with aqueous coker effluent from vessel 4 and gas from vessel 4 in mix valve 8 and passes through the lower part of heater 3. This airwater-gas system is oxidized in heater 3 whereby the chemical oxygen demand is removed from the gas and the aqueous coker effluent while the odor-forming constituents are destroyed. This oxidized stream is passed through heat exchanger 2 in heat exchange with the raw waste feed and thence through a pressure reducing valve 9 to a gas liquid separator 10. The gases and liquid from separator 10 may be discharged to the atmosphere and ditch respectively.

In another embodiment shown in dotted lines, the gas from vessel 4 can be passed through a pressure reducing valve 11 into the vessel 5 where it is mixed with the gases obtained in drying the coke.

The effluent from the coker (produced at conditions of 550 F. and 1,150 psig) has been oxidized with air at 550 F. and autogenous pressure to produce an oxidized effluent with a COD of 3802 mglO lliter and a pH 7.6. In considering the coker effluent alone (which had a COD of 72,076 mg/O /liter) this represents a COD reduction of 94.7 percent or basing it back on the COD of the charge it represents a reduction of upwards of 96 percent. The odor is also substantially removed. This oxidation was carried out in a batch operation. Operation on a continuous basis with excess air leads to essentially complete removal of COD.

The process of the invention is also suitable for treatment of other animal wastes such as pig wastes. The effluent from poultry feeding units can likewise be handled. A portion of the water produced from the described operation also can be used to wash down dairy barns, feed lots, and the like and then, in a sense, recycled through the whole system.

What is claimed is:

l. A process for converting pumpable animal waste to deodorized coke, odor-free effluent of low phosphorus content and odorless gases comprising bringing said waste into heat exchange relationship with said effluent to preheat the same, coking said preheated waste in a heating zone under pressure to thereby form a wet coke bed, a product gases phase and an aqueous effluent, se arating said wet coke, contactrng said coke with pressurized ot arr to deodorize and dry same, compressing said air, mixing said air with said aqueous efiluent and said product gases, oxidizing the resulting mixture to destroy odor-forming constituents present therein to thereby produce said odor-free effluent and said odorless gases.

2. The process according to claim 1, wherein said oxidation is carried out at about 550 F. under autogenous pressure.

'3. The process according to claim 1, wherein said pressurized hot air is heated by passage through said heating zone to a temperature of from about 250 F. to 350 F.

4. The process according to claim 1, wherein said hot air is passed over said wet coke bed at a flow rate sufficient to expand said coke bed and maintain same in an expanded condition.

5. The process according to claim 1, wherein sufficient air is used to provide excess oxygen. 

2. The process according to claim 1, wherein said oxidation is carried out at about 550* F. under autogenous pressure.
 3. The process according to claim 1, wherein said pressurized hot air is heated by passage through said heating zone to a temperature of from about 250* F. to 350* F.
 4. The process according to claim 1, wherein said hot air is passed over said wet coke bed at a flow rate sufficient to expand said coke bed and maintain same in an expanded condition.
 5. The process according to claim 1, wherein sufficient air is used to provide excess oxygen. 